Method of gold removal from electronic components

ABSTRACT

In some embodiments, a method removes gold plating on an electronic component. The method includes forming a gold and solder mixture on the electronic component via a first incrementally controlled heating procedure; incrementally cooling the electronic component via a first cooling procedure; wicking part or all of the gold and solder mixture from the electronic component to a metallic screen via a second incrementally controlled heating procedure; and incrementally cooling the electronic component via a second cooling procedure.

BACKGROUND

Connections on electronic components are typically plated in gold due tothe restriction of hazardous substances (i.e., lead) in electrical andelectronic equipment. However, in some environments, the gold platingbecomes brittle and can cause the failure of the connections on theelectronic components. The gold plating is typically removed by dippingthe connections on the electronic components in solder pots or handsoldering the connections. However, the dipping of the connections onthe electronic components in solder pots and the hand soldering of theconnections can cause thermal shock and damage the electroniccomponents. Thus, a need exists in the art for gold removal fromconnections on the electronic components with the features as describedherein.

SUMMARY

One approach provides a method for gold removal from electroniccomponents. The method includes (a) forming a gold and solder mixture onthe electronic component via a first incrementally controlled heatingprocedure; (b) incrementally cooling the electronic component via afirst cooling procedure; (c) wicking part or all of the gold and soldermixture from the electronic component to a metallic screen via a secondincrementally controlled heating procedure; and (d) incrementallycooling the electronic component via a second cooling procedure. In someexamples, the step (c) further includes positioning the electroniccomponent on the metallic screen to facilitate transfer of the gold andsolder mixture to the metallic screen. In other examples, the step (a)further includes temporarily adhering at least one of solder paste andsolder preform to a non-metallic substrate to form a metered solder pad;and positioning the electronic component on the metered solder pad. Inother examples, the step (c) further includes depositing flux on theelectronic component placed on the metallic screen.

Another approach provides a method for electronic thermal shockmanagement. The method includes (a) automatically unloading a pluralityof electronic components from an electronic component holder toindividual solder pads adhered to a non-metallic substrate; (b)positioning the non-metallic substrate on a first moving mechanism; (c)moving the non-metallic substrate through a first oven via the firstmoving mechanism to heat and cool the plurality of electronic componentsbased on a first temperature profile, wherein the heating of each of thesolder pads forms a gold and solder mixture on each of the plurality ofelectronic components; (d) placing the plurality of electroniccomponents on a metallic screen from the non-metallic substrate; (e)loading the metallic screen on a second moving mechanism; and (f) movingthe metallic screen through a second oven via the second movingmechanism to heat and cool the plurality of electronic components basedon a second temperature profile, wherein the heating of each of theelectronic components wicks part or all of the gold and solder mixtureto the metallic screen. In some examples, gold in the gold and soldermixture remaining in a solder joint of the electronic component afterstep (c) is substantially less than 3% gold by volume. In otherexamples, the method further includes (g) automatically loading theplurality of electronic components into the electronic component holder.

Any of the approaches described herein can include one or more of thefollowing examples.

In some examples, the non-metallic substrate includes a compositematerial.

In some examples, the metallic screen includes a flux coating tofacilitate transfer of the gold and solder mixture to the metallicscreen.

In other examples, the first incrementally controlled heating procedurehas a temperature range of substantially between 0.1 degrees Celsius persecond and 3.0 degrees Celsius per second and the first coolingprocedure has a temperature range of substantially between 0.1 degreesCelsius per second and 3.0 degrees Celsius per second.

In some examples, the second incrementally controlled heating procedurehas a temperature range of substantially between 0.1 degrees Celsius persecond and 3.0 degrees Celsius per second and the second coolingprocedure has a temperature range of substantially between 0.1 degreesCelsius per second and 3.0 degrees Celsius per second.

In other examples, the first incrementally controlled heating procedureis substantially the same as the second incrementally controlled heatingprocedure and the first cooling procedure is substantially the same asthe second cooling procedure.

The gold removal from electronic components technology described hereincan provide one or more of the following advantages. An advantage to thetechnology is the gradual heating and/or cooling of the electroniccomponents minimizes thermal stress on the electronic components.Another advantage to the technology is the gradual heating and/orcooling of the electronic components increases the useful lifespan ofthe electronic components.

Another advantage to the technology is the increased useful lifespan ofthe electronic components reduces the cost of the devices connected tothe electronic components by decreasing the maintenance cost anddown-time of the devices. Another advantage to the technology is therepeatable and safe method of diluting the gold from the electroniccomponents thereby decreasing the production cost while increasing theuseful environments in which the electronic component can be utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages will beapparent from the following more particular description of theembodiments, as illustrated in the accompanying drawings in which likereference characters refer to the same parts throughout the differentviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating the principles of the embodiments.

FIG. 1 is a flowchart of an exemplary process for gold removal fromelectronic components;

FIG. 2 is a flowchart of another exemplary process for gold removal fromelectronic components;

FIG. 3 is a flowchart of an exemplary process for electronic thermalshock management;

FIG. 4 is a block diagram of an exemplary metered solder pad;

FIGS. 5A-5E are block diagrams illustrating an exemplary process forgold removal from an electronic component; and

FIGS. 6A-6H are block diagrams illustrating an exemplary process forgold removal from electronic components.

DETAILED DESCRIPTION

The gold removal from electronic components technology described hereinenables the gradual heating and/or cooling of the electronic componentsto minimize damage and prolong the useful life of the electroniccomponents. The technology includes the placement of solder paste and/orprinted solder pads on a non-metallic substrate. The gold platedelectronic components are automatically or manually placed on theprinted solder pads. The printed solder pads are then mass reflowed(heated and/or cooled) to form a solder/gold mix on the printed solderpads. The printed solder pads are then placed on a fluxed metallicscreen. The fluxed metallic screen is then mass reflowed (heated and/orcooled) and the solder/gold mix wicks (e.g., capillary force, absorptionforce, etc.) to the hot fluxed metallic screen, thereby clearing theelectronic component of the gold plating and replacing the gold platingwith a solder/gold mix. The gold on the electronic components isadvantageously diluted and removed to prevent gold embrittlement of thesolder joint on the electronic component (e.g., removing the gold tofive micrometers on the electronic component, removing the gold to fiveto ten micrometers on the electronic component, etc.)

FIG. 1 is a flowchart 100 of an exemplary process for gold removal fromelectronic components. The process includes forming (110) a gold andsolder mixture (e.g., 60% gold and 40% solder, 40% gold and 60% solder,etc.) on the electronic component (e.g., surface-mount technologycomponent, integrated circuit component, leadless electronic component,etc.) via a first incrementally controlled heating procedure (e.g.,+2.0° Celsius per second heating, +200° Celsius per minute heating,etc.). The first heating procedure advantageously enables the electroniccomponent to be heated in a controlled fashion (i.e., in a temperaturecontrolled environment), thereby minimizing thermal stress on theelectronic components and maximizing the useful life of the electroniccomponent. The process further includes incrementally cooling (120) theelectronic component via a first cooling procedure (e.g., −1.0° Celsiusper second cooling, −100° Celsius per minute cooling, etc.). The firstcooling procedure advantageously enables the electronic component to becooled in a controlled fashion (i.e., in a temperature controlledenvironment), thereby minimizing thermal stress on the electroniccomponents and maximizing the useful life of the electronic component.

The process further includes wicking (130) part or all of the gold andsolder mixture from the electronic component to a metallic screen (e.g.,copper, iron, etc.), via a second incrementally controlled heatingprocedure (e.g., +3.0° Celsius per second heating, +400° Celsius perminute heating, etc.). The second heating procedure advantageouslyenables the electronic component to be heated in a controlled fashion(i.e., in a temperature controlled environment), thereby minimizingthermal stress on the electronic components and maximizing the usefullife of the electronic component. The part or all of the gold and soldermixture is attracted to the metallic screen due to a capillary forcebetween the gold and solder mixture and metallic screen. In other words,the metallic screen is advantageously a carrier to absorb the gold andsolder mixture from the electronic component. Although the process isdescribed as utilizing the metallic screen, any other type of materialthat provides for the capillary force can be utilized in the process.

The process further includes incrementally cooling (140) the electroniccomponent via a second cooling procedure (e.g., −2.0° Celsius per secondcooling, −400° Celsius per minute cooling, etc.). The second coolingprocedure advantageously enables the electronic component to be cooledin a controlled fashion (i.e., in a temperature controlled environment),thereby minimizing thermal stress on the electronic components andmaximizing the useful life of the electronic component. Although theprocess describes the first heating procedure, the first coolingprocedure, the second heating procedure, and the second coolingprocedure, the process can include any number and/or type of heatingand/or cooling techniques. For example, the process includes a steadystate heating of +1.0° Celsius per second throughout the process and asteady state cooling of −2.0° Celsius per second throughout the process.As another example, the process includes a heating of +1.0° Celsius persecond with an incremental increase of +2.0° Celsius per hour throughoutthe process and a steady state cooling of −2.0° Celsius per second withan incremental decrease of −0.5° Celsius per hour cooling throughout theprocess.

In some examples, the process includes temporarily adhering (112) atleast one of solder paste and solder perform to a non-metallic substrateto form a metered solder pad (e.g., stone, synthetic material, etc.). Inother examples, the process includes positioning (114) the electroniccomponent on the metered solder pad. The positioning (114) of theelectronic component can, for example, be performed by an operator(e.g., directly, indirectly, etc.) and/or an automated positioningmechanism (e.g., robot, factory machine, etc.).

In other examples, the process includes positioning (132) the electroniccomponent on the metallic screen to facilitate transfer of the gold andsolder mixture to the metallic screen. The metallic screen can be, forexample, a solder absorbing screen, a solder wicking screen, and/or anyother type of metallic screen. In some examples, the process includespositioning the electronic component on a first metallic screen tofacilitate absorption of the gold and solder mixture to the firstmetallic screen and positioning the electronic component on a secondmetallic screen to facilitate wicking of the gold and solder mixture tothe second metallic screen.

In some examples, the non-metallic substrate comprises a compositematerial (e.g., woven carbon fiber, metal matrix material, etc.). Inother examples, the metallic screen includes a flux coating tofacilitate transfer of the gold and solder mixture to the metallicscreen. The flux coating can, for example, remove surface oxidation onthe electronic component and/or facilitate the removal of the gold. Insome examples, the process is performed in a nitrogen environment (e.g.,nitrogen filled container, nitrogen stream blown on the electroniccomponent, etc.).

In some examples, the first incrementally controlled heating procedurehas a temperature range of substantially between 0.1 degrees Celsius persecond and 3.0 degrees Celsius per second and the first coolingprocedure has a temperature range of substantially between 0.1 degreesCelsius per second and 3.0 degrees Celsius per second. Although thisexample illustrates temperature ranges for the heating procedure and thecooling procedure, the technology described herein can utilize anycontrolled heating/cooling procedures (e.g., 0.001 degrees Celsius persecond, ±10.0 degrees Celsius, etc.). Table 1 illustrates an exemplaryheating procedure and cooling procedure.

TABLE 1 Exemplary Heating and Cooling Procedures Time Start TemperatureEnd Temperature Increase/Decrease 0 seconds  18° Celsius 118° Celsius+2.0° Celsius per through 50 second (Heating) seconds 50 seconds 118°Celsius 230° Celsius +3.0° Celsius per through 87 second (Heating)seconds 88 seconds 230° Celsius 175° Celsius −1.0° Celsius per through143 second (Cooling) seconds 144 seconds 175° Celsius  18° Celsius −2.0°Celsius per through 222.5 second (Cooling) seconds

In other examples, the second incrementally controlled heating procedurehas a temperature range of substantially between 0.1 degrees Celsius persecond and 3.0 degrees Celsius per second and the second coolingprocedure has a temperature range of substantially between 0.1 degreesCelsius per second and 3.0 degrees Celsius per second. Although thisexample illustrates temperature ranges for the heating procedure and thecooling procedure, the technology described herein can utilize anycontrolled heating/cooling procedures (e.g., 4.0 degrees Celsius persecond, 10.0 degrees Celsius per second, 0.00001 degrees Celsius persecond, ±50.0 degrees Celsius, etc.). Table 2 illustrates anotherexemplary heating procedure and cooling procedure.

TABLE 2 Exemplary Heating and Cooling Procedures Time Start TemperatureEnd Temperature Increase/Decrease 0 seconds  15° Celsius 125° Celsius+1.0° Celsius per through 115 second (Heating) seconds 116 seconds 125°Celsius 160° Celsius +1.5° Celsius per through 139 second (Heating)seconds 140 seconds 160° Celsius  15° Celsius −2.0° Celsius per through212.5 second (Cooling) seconds

In some examples, the first incrementally controlled heating procedureis substantially the same as the second incrementally controlled heatingprocedure and the first cooling procedure is substantially the same asthe second cooling procedure. In other examples, gold in the gold andsolder mixture remaining in a solder joint of the electronic componentafter the wicking of part or all of the gold and solder mixture from theelectronic component to the metallic screen is substantially less than3% gold by volume (e.g., ±1.0%, ±0.001%, etc.). The reduction of thegold and solder mixture to substantially less than 3% gold by volumeadvantageously dilutes and removes the gold to a level thatsubstantially prevents gold embrittlement of the solder joint on theelectronic component.

FIG. 2 is a flowchart 200 of another exemplary process for gold removalfrom electronic components. The process includes forming (210) a goldand solder mixture on the electronic component via a first incrementallycontrolled heating procedure. The process further includes incrementallycooling (220) the electronic component via a first cooling procedure.The process further includes wicking (230) part or all of the gold andsolder mixture from the electronic component to a metallic screen via asecond incrementally controlled heating procedure. The process furtherincludes incrementally cooling (240) the electronic component via asecond cooling procedure. In some examples, the process further includesdepositing (232) flux on the electronic component placed on the metallicscreen. The heating and cooling procedures described in this exemplaryprocess can utilize any of the examples and/or techniques as describedherein. In some examples, the high temperature of the heating proceduredescribed in this exemplary process is the melting temperature of thesolder.

FIG. 3 is a flowchart 300 of an exemplary process for electronic thermalshock management. The process includes automatically unloading (310) aplurality of electronic components from an electronic component holder(e.g., tape of components, package of components, stick of components,etc.) to individual solder pads adhered to a non-metallic substrate. Theprocess further includes positioning (320) the non-metallic substrate ona first moving mechanism. The process further includes moving (330) thenon-metallic substrate through a first oven (e.g., reflow oven,multi-zone reflow oven, hot plate device, hot air device, etc.) via thefirst moving mechanism to heat and cool the plurality of electroniccomponents based on a first temperature profile. The heating of each ofthe solder pads forms a gold and solder mixture on each of the pluralityof electronic components.

The process further includes placing (340) the plurality of electroniccomponents on a metallic screen from the non-metallic substrate. Theprocess further includes loading (350) the metallic screen on a secondmoving mechanism. The process further includes moving (360) the metallicscreen through a second oven via the second moving mechanism to heat andcool the plurality of electronic components based on a secondtemperature profile. The heating of each of the electronic componentswicks part or all of the gold and solder mixture to the metallic screen.In some examples, the process further includes automatically loading(370) the plurality of electronic components into the electroniccomponent holder. The heating and cooling profiles described in thisexemplary process can utilize any of the examples and/or techniques asdescribed herein. In other examples, the high temperature of the heatingprofiles described in this exemplary process is the melting temperatureof the solder pads. Table 3 illustrates exemplary oven zones associatedwith another exemplary heating procedure and cooling profiles.

TABLE 3 Exemplary Heating and Cooling Profiles Oven Start End Zone TimeTemperature Temperature Increase/Decrease 1 0 seconds  18° Celsius  75°Celsius +1.0° Celsius per through 57 second (Heating) seconds 2 58seconds  75° Celsius 225° Celsius +1.5° Celsius per through 158 second(Heating) seconds 5 159 seconds 225° Celsius  18° Celsius −2.0° Celsiusper through 262.5 second (Cooling) seconds 6 263 seconds  18° Celsius225° Celsius +1.0° Celsius per through 470 second (Heating) seconds 10471 seconds 225° Celsius 100° Celsius −2.0° Celsius per through 533.5second (Cooling) seconds 11 534 seconds 100° Celsius  18° Celsius −1.0°Celsius per through 616 second (Cooling) seconds

FIG. 4 is a block diagram of an exemplary metered solder pad 400. Themetered solder pad 400 includes a non-metallic substrate 410 and aplurality of electronic components A 420 a, B 420 b, C 420 c, D 420 d, E420 e, and F 420 f.

FIGS. 5A-5E are block diagrams illustrating an exemplary process forgold removal from an electronic component. FIG. 5A illustrates anexemplary solder paste and/or solder preform 530 a temporarily adheredto a non-metallic substrate 510 (also referred to as forming a meteredsolder pad). An electronic component 520 is positioned on the solderpaste and/or solder preform 530 a. FIG. 5B illustrates a gold and soldermixture 540 b formed on the non-metallic substrate 510 via a firstincrementally controlled heating procedure. FIG. 5C illustrates theelectronic component 520 and the gold and solder mixture 540 b placed ona metallic screen 550 c. FIG. 5D illustrates flux 560 d deposited on themetallic screen 550 c. FIG. 5E illustrates part or all of the gold andsolder mixture 540 e from the electronic component wicked to themetallic screen 550 c via a second incrementally controlled heatingprocedure.

FIGS. 6A-6H are block diagrams illustrating an exemplary process forgold removal from electronic components. FIG. 6A illustrates anelectronic component holder 610 a holding a plurality of electroniccomponents A 610 a, B 610 b through Z 610 z (generally referred to aselectronic components 610). FIG. 6B illustrates the electroniccomponents 610 placed on individual solder pads A 612 a, B 612 b throughZ 612 z, respectively (generally referred to as solder pads 612), on anon-metallic substrate 630 b. FIG. 6C illustrates the non-metallicsubstrate 630 b positioned on a moving mechanism 640 c and movement (604c) of the non-metallic substrate 630 b through an oven 650 c. FIG. 6Dillustrates the non-metallic substrate 630 b after movement (604 d)through the oven 650 c. As illustrated in FIG. 6D, the heating of thesolder pads 612 forms a gold and solder mixture A 614 a, B 614 b throughZ 614 z (generally referred to as gold and solder mixture 614) on thenon-metallic substrate 630 b, respectively.

FIG. 6E illustrates the electronic components 610 and the gold andsolder mixture 614 placed on a metallic screen 660 e. FIG. 6Fillustrates the metallic screen 660 e loaded on a moving mechanism 670 fFIG. 6G illustrates movement (606 g) of the metallic screen 660 ethrough an oven 680 g. FIG. 6H illustrates the metallic screen 660 eafter movement (606 h) through the oven 680 g. As illustrated in FIG.6H, the heating of the electronic components 610 and the gold and soldermixture 614 wicks the gold and solder mixture A 616 a, B 616 b through Z616 z to the metallic screen 660 e.

Comprise, include, and/or plural forms of each are open ended andinclude the listed parts and can include additional parts that are notlisted. And/or is open ended and includes one or more of the listedparts and combinations of the listed parts.

One skilled in the art will realize the invention may be embodied inother specific forms without departing from the spirit or essentialcharacteristics thereof. The foregoing embodiments are therefore to beconsidered in all respects illustrative rather than limiting of theinvention described herein. Scope of the invention is thus indicated bythe appended claims, rather than by the foregoing description, and allchanges that come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed is:
 1. A method for removing gold plating on anelectronic component, the method comprising: (a) forming a gold andsolder mixture on the electronic component via a first incrementallycontrolled heating procedure; (b) incrementally cooling the electroniccomponent via a first cooling procedure; (c) wicking part or all of thegold and solder mixture from the electronic component to a metallicscreen via a second incrementally controlled heating procedure; and (d)incrementally cooling the electronic component via a second coolingprocedure.
 2. The method of claim 1, wherein the step (c) furthercomprising: positioning the electronic component on the metallic screento facilitate transfer of the gold and solder mixture to the metallicscreen.
 3. The method of claim 1, wherein the step (a) furthercomprising: temporarily adhering at least one of solder paste and solderpreform to a non-metallic substrate to form a metered solder pad; andpositioning the electronic component on the metered solder pad.
 4. Themethod of claim 3, wherein the non-metallic substrate comprises acomposite material.
 5. The method of claim 1, wherein the step (c)further comprising: depositing flux on the electronic component placedon the metallic screen.
 6. The method of claim 1, wherein the metallicscreen includes a flux coating to facilitate transfer of the gold andsolder mixture to the metallic screen.
 7. The method of claim 1, whereinthe first incrementally controlled heating procedure has a temperaturerange of substantially between 0.1 degrees Celsius per second and 3.0degrees Celsius per second and the first cooling procedure has atemperature range of substantially between 0.1 degrees Celsius persecond and 3.0 degrees Celsius per second.
 8. The method of claim 1,wherein the second incrementally controlled heating procedure has atemperature range of substantially between 0.1 degrees Celsius persecond and 3.0 degrees Celsius per second and the second coolingprocedure has a temperature range of substantially between 0.1 degreesCelsius per second and 3.0 degrees Celsius per second.
 9. The method ofclaim 1, wherein the first incrementally controlled heating procedure issubstantially the same as the second incrementally controlled heatingprocedure and the first cooling procedure is substantially the same asthe second cooling procedure.
 10. The method of claim 1, wherein gold inthe gold and solder mixture remaining in a solder joint of theelectronic component after step (c) is substantially less than 3% goldby volume.